Phytochemicals are broadly known to be any chemical or nutrient derived from a plant source. The term phytochemicals may also refer to compounds found in plants that are not required for normal functioning of the human body but that may have a positive impact on body function. For example, phytochemicals may promote immune system function, possess antibiotic, antiviral, antineoplastic or antiinflammatory activity; and be associated with the treatment or prevention of maladies such as cancer or cardiovascular disease. Given the wealth of possible beneficial effects of phytochemicals, these compounds may be incorporated into a variety of consumer products such as for example nutritional supplements such as vitamins and topical protectants such as sunscreen.
It is well established that UV radiation with wavelengths between 290 nm and 400 nm damages the human epidermis. Even brief exposure to UVB radiation (wavelengths between about 290 nm and about 320 nm) can cause sunburn, while long-term exposure to UVA radiation (wavelengths between about 320 nm and about 400 nm) can cause skin cancer (melanoma) and premature aging of the skin (including wrinkling, loss of elasticity, and pigment changes). Thus, there is a significant demand for inexpensive, effective sunblocks and sunscreens.
The most commonly used sunscreens are UV filters, which typically organic compounds are incorporated at levels of about 2-15% into topical formulations. A disadvantage of UV filters is that each organic compound has a limited range of effective UV absorptivity, rendering each compound better suited for either UVA protection or UVB protection but not both. The advantage of the UV filtering molecules, however, is that they can be engineered to provide sunscreens with desirable physical appearance, solubility, and water resistant properties.
One such approach to the formation of effective sunscreens entails the formation of structured lipids with specific UV-absorbing properties. It is known that covalent substitution of ferulic acid onto the glycerol backbone of triacylglycerols generates commercially-useful ultraviolet light absorbing lipids. As disclosed in U.S. Pat. No. 6,346,236, which is incorporated herein by reference, one technique for feruloylation of vegetable oils entails a prolonged lipase treatment of ethyl ferulate and triacylglycerol. However, this reaction, a transesterification, is slow and takes on the order of days to reach equilibrium at 60° C.
Thus, there is an ongoing need for improved phytochemical-containing compositions and methods of making same. Additionally, in order to improve the commercial value of sunscreens and other phytochemical-containing products produced from vegetable oils, it remains desirable to enhance the rate and yield of the transesterification reaction.